Pigment and process of making the same.



. r my UNITED STATES PATENT OFFICE.

RENE BOHN, OF MANNHEIM, GERMANY, ASSIGNOR T BADISCHE ANILIN & SODAFABRIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A CORPORATION.

PIGMENT AND PROCESS OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

Be it. known that I, Rnmi Bonn, doctor of philosophy and chemist,citizen of the Swiss Republic, residing at Mannheim, Germany, haveinvented new and useful Improvements in Pigments and Processes of Makingthe Same, of which the following is a specification.

It is known that indanthrene and similar vat coloring matters can bereduced to their soluble leuco compounds by beating them with a reducingagent in the presence of alkali and water, indeed, the principalprocesses for dyeing and printing wit indanthrone are based upon thistreatment. The indanthrene dye vat is usually pre awed by rcduein"indanthrene by means 0i sodium hydrosidtite in alkaline solution,sufiicient water being taken to permit readily of complete solution. Ihave discovered that indanthrenc and other vat coloring matters of theanthracene series (either as such or in the form of their leucocompounds, which for the purpose of my invention are equivalent) can bebrought into a condition especially suitable for use as pigments bybeating them with a carbohydrate, such for instance as gra )0 sugar, int 1c )resence of alkali, but to PlOt' uce this effect the quantity ofsolvent used should be so chosen that as little as possible of thecolorin matter oes into solution, and to this on air can e assed throughthe reaction liquid either uring the heating or subsequently.Indanthrene which has been thus treated possesses a greater coloringpower and also a brighter and greener shade of blue than before suchtreatment.

As instances of vat coloring matters other than indanthrene which can betreated according to this invention, I mention violanthrone coloringmatters and those obtainable by heatin" aminoanthraquinones with a metalin the presence of sulfuric acid, but

the coloring matter is not affected to the same degree in all cases.

My new products are characterized by the following properties. Each ofthem is insoluble in water and in dilute acids and alkalis, slightlysoluble in boiling nitrobenzene and soluble in alkaline hydrosulfitesolution, forming a vat which dyes cotton. On being dissolved inalkaline hydrosulfite solution and then precipitated therefrom by meansof a rapid current of air, they each Specification of Letters Patent.

Application filed January 27, 1909. Serial No. 474,486.

Patented Mar. 11, 1913.

yield a. product which when employed as a pigment possesses considerablyless covering power than my corresponding new product.

The following example will serve to illustrate further the nature of myinvention and how it can be carried into practical effect, but theinvention is not confined to this example. The parts are by weight.

Dilute one thousand parts of a ten per cent. paste of indanthrene blueRS with nine thousand parts of water, add nine hundred parts of athirty-five per cent. caustic soda. solution and five hundred parts ofgrape sugar, and boil for from thirty, to sixty minutes. Should anyportion of the coloring matter be in solution, pass air through thereaction mixture until the filtrate of a test portion is colorless. Thenfilter the reaction mass and wash the residue well with water. If nopart of the coloring matter be dissolved, the assing of air through themixture can be dispensed with.

Now what I claim is 1. The rocess of preparing vat coloring matters ofthe anthracene series suitable for use as a pigment by heating such vatcoloring matter with a carbohydrate and alkali and an amount of solventinsufiicicnt to dissolve the coloring matters, substantially asdescribed.

2. The process of preparing vat. coloring matter of the anthraceneseries suitable for use as a pigment by heating such vat coloring matterwith grape sugar and caustic soda and an amount of solvent insuilicientto dissolve the coloring matter, substantially as described.

3. The process of preparing indanthrenc suitable for use as a pi ment byheating the said indanthrenc with grape sugar and caustic alkali andanamount of solvent insuilicient to dissolve the indanthrene,substantially as described.

4. As a new product a pigment consisting of an indanthrcne coloringmatter in a new physical condition, being insoluble in water and indilute acids and alkalis, slightly soluble in boiling nitrobenzene andsoluble in alkaline hydrosulfite solution, forming a vat which d ascotton, and on being dissolved in alkaline hydrosulfite solution andprecipitated therefrom by means of a rapid current of air yields aproduct which when employed as a pigment possesses considerably lesscovering power than my new product.

5. As a new product a pigment consisting of indanthrene blue in anewphysical condition, bein insoluble in water and in dilute acids analkalis, slightly soluble in boiling nitrobenzene and soluble inalkaline hydrosulfite solution, forming a vat which dyes cotton blue,and which upon being dissolved in alkaline h drosulfite solution andbeing precipitated t erefrom by means of a rapid current of air givesrise to a product which, when employed as a pigment possessesconsiderably less covering power and a less greenish tint of blue thanmy new product.

In testimony whereof I have hereunto set m hand in the presence of twosubscribing witnesses.

RENE BOHN.

Witnesses:

J. ALEo. LLOYD, TERESA CA'rrURANI.

Copies of this patent may be obtained for live cents each, by addressingthe Commissioner 0! Patents, Washington, D. 0.

